A Professor Morris Puzzle is more than the problem you see. Solving the problem is the starting point for further discussion and investigation. Notes are provided to support that process.
Multiplication, commutative law
Task Centre Connection
Task 9: Row Points
Task 17: Truth Tiles 2
Task 19: Cookie Count
Task 30: Truth Tiles
Task 123: Bob's Buttons
Task 235: Tables for 25
Make a model, write an equation
Puzzle 9 has a similar problem involving five hands, each with four fingers. Clearly the answer to each puzzle is 20. Also the pair of puzzles shows that 4 x 5 = 5 x 4. More importantly the puzzles demonstrate the importance of context, for in these cases 4x5 does not mean the same as 5x4.